It has been a common practice in the welding machine industry to build welding machines with custom tooling as an integral part of the welding machine. In this practice, especially in connection with resistance and MIG welding machines, each machine is dedicated to the manufacture of a particular part and is not useable for manufacture of other parts. The working area of such a dedicated machine includes an attached assembly of fixtures and tools specifically made, located and adjusted to produce the parts to which the machine is dedicated. The entire machine, from heavy frame to built-in precision fixtures is treated as capital equipment on the financial books of the purchaser. When the parts produced by the dedicated machine are no longer needed, the entire machine is generally scrapped.
Previously, there had been a longstanding need in the industry to overcome the disadvantages which accompany the practice of using dedicated welding machines such as the economic loss from scrapping the entire machine when the tools and fixtures are no longer usable because of wear and tear or because of termination of production of the part to which the machine is dedicated. A general solution to this problem is disclosed in U.S. Pat. No. 6,512,195 which discloses an electric welding machine that has a base operating machine which can accept different tooling modules so that only the tooling module and not the entire welding machine can be replaced when switching between different welding programs or operations.
In the welding machine of the U.S. Pat. No. 6,512,195 patent, the tooling module can be transferred to and from the base operating machine from a module transfer cart, or tooling cart, that is useful in transporting and storing the tooling module when not in use. To connect a particular tooling module to the base operating machine for use in welding parts, the tooling cart containing the tooling module is wheeled up to the base operating machine. A pair of alignment pins on the tooling cart engage and insert into corresponding alignment sockets on the base operating machine. This helps insure proper alignment of the cart and base operating machine so that the tooling module can be slid off the cart and onto the base operating machine. Although this arrangement provides vertical and lateral alignment of the tooling cart and base operating machine, it still allows for relative movement of the tooling cart toward and away from the base operating machine during tooling module transfer. Additionally, this arrangement does not provide any means for positively latching the tooling module to the tooling cart to maintain the tooling module in place and prevent the tooling module from shifting on the cart as the tooling cart is moved. When a particular tooling module is not in use on a base operating machine, it is typically stored on a tooling cart until needed. This enables easy transportation and storage of the tooling module without requiring heavy lifting equipment. However, this arrangement does require a dedicated cart for each tooling module.
When switching between tooling modules, new control programming is typically required for the welding machine. As is known, welding machines typically include a programmable logic controller (PLC) that is programmed to carry out one or more specific welding sequences in which the PLC controls operation of both the welding controller and the various solenoid valves used to drive pneumatic cylinders or other actuators that load, manipulate, weld, and unload a part. Programming of the PLC has typically been done using ladder logic, with a separate set of ladder logic being written and loaded into the PLC for each different tooling module used.
It is a general object of this invention to improve upon some of the features of the modular welding machines discussed above.